Publications by authors named "Jianqi Li"

118 Publications

Recent advances in β-catenin/BCL9 protein-protein interaction inhibitors.

Authors:
Hao Zhang Ya Bao Chenglong Liu Jianqi Li Di Zhu Qingwei Zhang

Future Med Chem 2021 Apr 14. Epub 2021 Apr 14.

Novel Technology Center of Pharmaceutical Chemistry, Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry, Shanghai, 201203, China.

Wnt/β-catenin signaling is crucial both in normal embryonic development and throughout the life of an organism. Moreover, aberrant Wnt signaling has been associated with various diseases, especially cancer and fibrosis. Recent research suggests that direct targeting of the β-catenin/BCL9 protein-protein interaction (PPI) is a promising strategy to block the Wnt pathway. Progress in understanding the cocrystalline complex and mechanism of action of the β-catenin/BCL9 interaction facilitates the discovery process of its inhibitors, but only a few inhibitors have been reported. In this review, the discovery and development of β-catenin/BCL9 PPI inhibitors in the areas of drug design, structure-activity relationships and biological and biochemical properties are summarized. In addition, perspectives for the future development of β-catenin/BCL9 PPI inhibitors are explored.
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http://dx.doi.org/10.4155/fmc-2020-0357DOI Listing
April 2021

Magnetic resonance quantitative susceptibility mapping in the evaluation of hepatic fibrosis in chronic liver disease: a feasibility study.

Authors:
Zheng Qu Shuohui Yang Feng Xing Rui Tong Chenyao Yang Rongfang Guo Jiling Huang Fang Lu Caixia Fu Xu Yan Stefanie Hectors Kelly Gillen Yi Wang Chenghai Liu Songhua Zhan Jianqi Li

Quant Imaging Med Surg 2021 Apr;11(4):1170-1183

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai, China.

Background: Noninvasive methods for the early diagnosis and staging of hepatic fibrosis are needed. The present study aimed to investigate the alteration of magnetic susceptibility in the liver of patients with various fibrosis stages and to evaluate the feasibility of using susceptibility to stage hepatic fibrosis.

Methods: A total of 30 consecutive patients with chronic liver diseases (CLDs) underwent magnetic resonance imaging (MRI) and liver biopsy evaluation of hepatic fibrosis, necroinflammatory activity, iron load, and steatosis. Quantitative susceptibility mapping (QSM), R2* and proton density fat fraction (PDFF) images were postprocessed from the same gradient-echo data for quantitative tissue characterization using region of interest (ROI) analysis. The differences for MRI measurements between cohorts of non-significant (Ishak-F <3) and significant fibrosis (Ishak-F ≥3) and the correlation of MRI measurements with fibrosis stages and necroinflammatory activity grades were tested. Receiver operating characteristic (ROC) analysis was also performed.

Results: There was a significant difference in liver susceptibility between the cohorts of significant and non-significant fibrosis (Z=-2.880, P=0.004). A moderate negative correlation between the stages of liver fibrosis and liver susceptibility was observed (r=-0.471, P=0.015). Liver magnetic susceptibility differentiated non-significant from significant hepatic fibrosis with an area under the receiver operating curve (AUC) of 0.836 (P=0.004). A highly sensitive diagnostic performance with an AUC of 0.933 was obtained using magnetic susceptibility and PDFF together (P<0.001).

Conclusions: A noninvasive liver QSM-based evaluation promises an accurate assessment of significant fibrosis in patients with CLDs.
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http://dx.doi.org/10.21037/qims-20-720DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7930689PMC
April 2021

Design, synthesis and biological evaluation of brain penetrant benzazepine-based histone deacetylase 6 inhibitors for alleviating stroke-induced brain infarction.

Authors:
Zheng Guo Zixue Zhang Yi Zhang Guan Wang Ziyi Huang Qinwei Zhang Jianqi Li

Eur J Med Chem 2021 Mar 17;218:113383. Epub 2021 Mar 17.

Novel Technology Center of Pharmaceutical Chemistry, Shanghai Institute of Pharmaceutical Industry, Shanghai, 201203, China; Shanghai Engineering Research Center of Pharmaceutical Process, Shanghai, 201203, China. Electronic address:

Histone deacetylase 6 (HDAC6) has become a promising therapeutic target for central nervous system diseases due to its more complex protein structure and biological functions. However, low brain penetration of reported HDAC6 inhibitors limits its clinical application in neurological disorders. Therefore, the benzazepine, a brain-penetrant rigid fragment, was utilized to design a series of selective HDAC6 inhibitors to improve brain bioavailability. Various synthetic strategies were applied to assemble the tetrahydro-benzazepine ring, and 22 compounds were synthesized. Among them, compound 5 showed low nanomolar potency and strong isozyme selectivity for the inhibition of HDAC6 (IC = 1.8 nM, 141-fold selectivity over HDAC1) with efficient binding patterns like coordination with the zinc ion and π-π stacking effect. Western blot results showed it could efficiently transport into SH-SY5Y cells and selectively enhance the acetylation level of α-tubulin with a moderate effect on Histone H3. Notably, pharmacokinetic studies demonstrated that compound 5 (brain/plasma ratio of 2.30) had an excellent ability to penetrate the blood-brain barrier of C57 mice. In male rats with transient middle cerebral artery occlusion (MCAO), compound 5 significantly reduced the cerebral infarction from 21.22% to 11.47% and alleviated neurobehavioral deficits in post-ischemic treatment, which provided a strong rationale for pursuing HDAC6-based therapies for ischemic stroke.
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http://dx.doi.org/10.1016/j.ejmech.2021.113383DOI Listing
March 2021

Structural characterization and statistical properties of jammed soft ellipsoid packing.

Authors:
Yinfei Chen Ming Yuan Zhichao Wang Yu Zhao Jianqi Li Bingwen Hu Chengjie Xia

Soft Matter 2021 Mar;17(10):2963-2972

Shanghai Key Laboratory of Magnetic Resonance, Institute of Materials, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, P. R. China.

The jamming transition and jammed packing structures of hydrogel soft ellipsoids are studied using magnetic resonance imaging techniques. As the packing fraction increases, the fluctuation of local free volume decreases and the fluctuation of particle deformation increases. Effective thermodynamic quantities are obtained by characterizing these fluctuations using k-gamma distributions based on an underlying statistical model for granular materials. Surprisingly, the two granular temperatures measuring the relative fluctuations of both free volume and particle deformation remain basically unchanged as the packing fraction increases. The total configurational entropy is also approximately constant for packing with different packing fractions. The significantly different behaviors of these effective thermodynamic quantities compared with hard sphere systems are further attributed to a statistically affine structural transformation of the packing structures along with particle deformations when the packing fraction changes.
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http://dx.doi.org/10.1039/d0sm01699cDOI Listing
March 2021

The microstructure of quasi-one-dimensional superconductor KCrAsprepared by K-ion deintercalation.

Authors:
Lu Zhang Jun Li Qing-Ge Mu Tong Liu Dong Yang Chunhui Zhu Zhian Ren Huanfang Tian Zian Li Jianqi Li Yang Huaixin

J Phys Condens Matter 2021 Feb 15. Epub 2021 Feb 15.

Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences Institute of Physics, Zhongguancun street, Beijing, 100190, CHINA.

The microstructure of quasi-one-dimensional KCr3As3 (133) superconductors, which were prepared by chemical cation deintercalation from their counterpart K2Cr3As3 (233) compounds, are investigated using scanning transmission electron microscopy. The nominal KCr3As3 crystals generally exhibit irregular nanoscale 133-phase domains accompanied by an amorphous As-deficient phase and cracks as a result of alkali cation deintercalation processes. Analysis of local defective structures reveals the existence of an intermediate state in the transformation from 233 to 133 phase and a possible K-deficient 233-type structure as a nanoscale cluster. Our microscopic investigations offer insight into the microstructure of KCr3As3 and the alkali metal cation deintercalation processes.
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http://dx.doi.org/10.1088/1361-648X/abe64dDOI Listing
February 2021

Epithelioid trophoblastic tumor coexisting with choriocarcinoma around an abdominal wall cesarean scar: a case report and review of the literature.

Authors:
Chunfeng Yang Jianqi Li Yuanyuan Zhang Hanzhen Xiong Xiujie Sheng

J Med Case Rep 2020 Oct 5;14(1):178. Epub 2020 Oct 5.

Department of Obstetrics and Gynecology, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.

Background: Mixed gestational trophoblastic neoplasms are extremely rare and comprise a group of fetal trophoblastic tumors including choriocarcinomas, epithelioid trophoblastic tumors, and placental site trophoblastic tumors. We present a case of a patient with extrauterine mixed gestational trophoblastic neoplasm adjacent to the abdominal wall cesarean scar. On the basis of a literature review, this type of case has never been reported before due to the unique lesion location and low incidence.

Case Presentation: Our patient was a 39-year-old Chinese woman who had a history of two cesarean sections and one miscarriage. She had a recurrent anterior abdominal wall mass around her cesarean scar, and the mass was initially suspected of being choriocarcinoma of unknown origin. The patient had concomitant negative or mildly increased serum β-human chorionic gonadotropin at follow-up and no abnormal vaginal bleeding or abdominal pain. However, she underwent local excision twice and had two courses of chemotherapy with an etoposide and cisplatin regimen. She finally opted for exploratory laparotomy with abdominal wall lesion removal, subtotal hysterectomy, bilateral salpingectomy, and left ovarian cyst resection, which showed the abdominal wall lesion, whose components were revealed by microscopy and immunohistochemical staining to be approximately 90% epithelioid trophoblastic tumors and 10% choriocarcinomas from a solely extrauterine mixed gestational trophoblastic neoplasm around an abdominal wall cesarean scar.

Conclusions: It is worth noting whether epithelioid trophoblastic tumor exists in the setting of persistent positive low-level β-human chorionic gonadotropin. More studies are required to provide mechanistic insights into these mixed gestational trophoblastic neoplasms.
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http://dx.doi.org/10.1186/s13256-020-02485-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534162PMC
October 2020

Quantitative Measurement of Metal Accumulation in Brain of Patients With Wilson's Disease.

Authors:
Gaiying Li Rong Wu Rui Tong Binshi Bo Yu Zhao Kelly M Gillen Pascal Spincemaille Yixuan Ku Yasong Du Yi Wang Xiaoping Wang Jianqi Li

Mov Disord 2020 10 18;35(10):1787-1795. Epub 2020 Jul 18.

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai, China.

Background: Currently, no study has evaluated metal accumulation in the brains of patients with Wilson's disease by using quantitative susceptibility mapping at 3T MRI. The objectives of this study were to qualitatively and quantitatively evaluate changes in magnetic susceptibility and R2* maps in deep gray matter nuclei to discriminate Wilson's disease patients from healthy controls and to evaluate their sensitivities in diagnosing Wilson's disease.

Methods: Magnetic susceptibility and R2* maps and conventional T1-weighted, T2-weighted, and T2-weighted fluid-attenuated inversion recovery images were obtained from 17 Wilson's disease patients and 14 age-matched healthy controls on a 3T MRI scanner. Differences between Wilson's disease and healthy control groups in susceptibility and R2* values in multiple deep nuclei were evaluated using a Mann-Whitney U test and receiver operating characteristic curves. The correlations of susceptibility and R2* values with Unified Wilson's Disease Rating Scale score were also performed.

Results: Magnetic susceptibility and R2* can effectively distinguish different types of signal abnormalities. Magnetic susceptibility and R2* values in multiple deep nuclei of Wilson's disease patients were significantly higher than those in healthy controls. Magnetic susceptibility value in the substantia nigra had the highest area under the curve (0.888). There were positive correlations of the Unified Wilson's Disease Rating Scale score with susceptibility values in the caudate nucleus (r = 0.757, P = 0.011), putamen (r = 0.679, P = 0.031), and red nucleus (r = 0.638, P = 0.047), as well as R2* values in the caudate nucleus (r = 0.754, P = 0.012).

Conclusions: Quantitative susceptibility mapping at 3T could be a useful tool to evaluate metal accumulation in deep gray matter nuclei of Wilson's disease patients. © 2020 International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.28141DOI Listing
October 2020

Dynamics of chiral state transitions and relaxations in an FeGe thin plate via in situ Lorentz microscopy.

Authors:
Ke Chai Zi-An Li Ruibin Liu Bingsuo Zou Michael Farle Jianqi Li

Nanoscale 2020 Jul;12(27):14919-14925

Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences, Beijing 100190, China and Yangtze River Delta Physics Research Center Co., Ltd. - Liyang, Jiangsu, 213300, China and Songshan Lake Materials Laboratory - Dongguan, Guangdong, 523808, China.

Studying the magnetic transition between different topological spin textures in noncentrosymmetric magnets under external stimuli is an important topic in chiral magnetism. Here, using in situ Lorentz transmission electron microscopy (LTEM) we directly visualize the thermal-driven magnetic transitions and dynamic characteristics in FeGe thin plates. A novel protocol-dependent phase diagram of FeGe thin plates was obtained via pulsed laser excitation. Moreover, by setting the appropriate specimen temperature, the relaxation of chiral magnetic states in FeGe specimens was recorded and analyzed with an Arrhenius-type relaxation mechanism. We present the field-dependent activation energy barriers for chiral state transitions and the magnetic transition pathways of these spin textures for FeGe thin plates. Our results unveil the effects of thermal excitation on the topological spin texture transitions and provide useful information about magnetic dynamics of chiral magnetic state relaxation.
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http://dx.doi.org/10.1039/d0nr03278fDOI Listing
July 2020

Effectiveness of fat suppression using a water-selective binomial-pulse excitation in chemical exchange saturation transfer (CEST) magnetic resonance imaging.

Authors:
Yu Zhao Zhongliang Zu Zhichao Wang Zhenzhi Liu Bin Guo Xu Yan Daniel F Gochberg Jianqi Li

MAGMA 2020 Dec 27;33(6):809-818. Epub 2020 May 27.

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062, China.

Purpose: The purpose of this study was to characterize the individual contribution of multiple fat peaks to the measured chemical exchange saturation transfer (CEST) signal when using water-selective binomial-pulse excitation and to determine the effects of multiple fat peaks in the presence of B inhomogeneity.

Methods: The excitation profiles of multiple binomial pulses were simulated. A CEST sequence with binomial-pulse excitation and modified point-resolved spectroscopy localization was then applied to the in vivo lumbar spinal vertebrae to determine the signal contributions of three distinct groups of lipid resonances. These confounding signal contributions were measured as a function of the irradiation frequency offset to determine the effect of the multi-peak nature of the fat signal on CEST imaging of exchange sites (at 1.0, 2.0 and 3.5 ppm) and robustness in the presence of B inhomogeneity.

Results: Numerical simulations and in vivo experiments showed that water excitation (WE) using a 1-3-3-1 (WE-4) pulse provided the broadest signal suppression, which provided partial robustness against B inhomogeneity effects. Confounding fat signal contributions to the CEST contrasts at 1.0, 2.0 and 3.5 ppm were unavoidable due to the multi-peak nature of the fat signal. However, these CEST sites only suffer from small lipid artifacts with ∆B spanning roughly from  - 50 to 50 Hz. Especially for the CEST site at 3.5 ppm, the lipid artifacts are smaller than 1% with ∆B in this range.

Conclusion: In WE-4-based CEST magnetic resonance imaging, B inhomogeneity is the limiting factor for fat suppression. The CEST sites at 1.0, 2.0 ppm and 3.5 ppm unavoidably suffer from lipid artifacts. However, when the ∆B is confined to a limited range, these CEST sites are only affected by small lipid artifacts, which may be ignorable in some cases of clinical applications.
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http://dx.doi.org/10.1007/s10334-020-00851-7DOI Listing
December 2020

Disrupted functional connectivity between sub-regions in the sensorimotor areas and cortex in migraine without aura.

Authors:
Zhaoxia Qin Jingjing Su Xin-Wei He Shiyu Ban Qian Zhu Yangyang Cui Jilei Zhang Yue Hu Yi-Sheng Liu Rong Zhao Yuan Qiao Jianqi Li Jian-Ren Liu Xiaoxia Du

J Headache Pain 2020 May 6;21(1):47. Epub 2020 May 6.

Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, School of Physics and Electronic Science, East China Normal University, 3663 North Zhong-Shan Road, 200062, Shanghai, People's Republic of China.

Background: Migraine is a severe and disabling brain disorder, and the exact neurological mechanisms remain unclear. Migraineurs have altered pain perception, and headache attacks disrupt their sensory information processing and sensorimotor integration. The altered functional connectivity of sub-regions of sensorimotor brain areas with other brain cortex associated with migraine needs further investigation.

Methods: Forty-eight migraineurs without aura during the interictal phase and 48 age- and sex-matched healthy controls underwent resting-state functional magnetic resonance imaging scans. We utilized seed-based functional connectivity analysis to investigate whether patients exhibited abnormal functional connectivity between sub-regions of sensorimotor brain areas and cortex regions.

Results: We found that patients with migraineurs without aura exhibited disrupted functional connectivities between the sensorimotor areas and the visual cortex, temporal cortex, posterior parietal lobule, prefrontal areas, precuneus, cingulate gyrus, sensorimotor areas proper and cerebellum areas compared with healthy controls. In addition, the clinical data of the patients, such as disease duration, pain intensity and HIT-6 score, were negatively correlated with these impaired functional connectivities.

Conclusion: In patients with migraineurs without aura, the functional connectivities between the sensorimotor brain areas and other brain regions was reduced. These disrupted functional connectivities might contribute to abnormalities in visual processing, multisensory integration, nociception processing, spatial attention and intention and dysfunction in cognitive evaluation and modulation of pain. Recurrent headache attacks might lead to the disrupted network between primary motor cortex and temporal regions and between primary somatosensory cortex and temporal regions. Pain sensitivity and patient quality of life are closely tied to the abnormal functional connectivity between sensorimotor regions and other brain areas.
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http://dx.doi.org/10.1186/s10194-020-01118-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7203097PMC
May 2020

The intercalation of 1,10-phenanthroline into layered NiPSvia iron dopant seeding.

Authors:
Xiaoping Ma Lu Zhang Chengchao Xu Qingxin Dong Richard I Walton Zian Li Honglong Shi Genfu Chen Jiangping Hu Jianqi Li Huaxin Yang

Chem Commun (Camb) 2020 Apr 25;56(33):4603-4606. Epub 2020 Mar 25.

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.

Using 2% percent of iron dopants as reaction active sites yields a series of single crystals of 1,10-phenanthroline intercalated NiPS, via a solution reaction with aniline chloride, not possible by a direct reaction. Experimental magnetic susceptibility measurements demonstrate that 1,10-phenanthroline intercalation suppresses the anti-ferromagnetism ordering at around 150 K in FeNiPS, and gives rise to a ferrimagnetic phase transition at a temperature around 75 K. An intercalation mechanism is proposed for the reaction, and this dopant seeding method provides a new approach for intercalation into layered materials.
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http://dx.doi.org/10.1039/d0cc00636jDOI Listing
April 2020

Magnetic quantification of single-crystalline Fe and Co nanowires via off-axis electron holography.

Authors:
Ke Chai Zi-An Li Wenting Huang Gunther Richter Ruibin Liu Bingsuo Zou Jan Caron András Kovács Rafal E Dunin-Borkowski Jianqi Li

J Chem Phys 2020 Mar;152(11):114202

Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.

Investigating the local micromagnetic structure of ferromagnetic nanowires (NWs) at the nanoscale is essential to study the structure-property relationships and can facilitate the design of nanostructures for technology applications. Herein, we synthesized high-quality iron and cobalt NWs and investigated the magnetic properties of these NWs using off-axis electron holography. The Fe NWs are about 100 nm in width and a few micrometers in length with a preferential growth direction of [100], while the Co NWs have a higher aspect-ratio with preferential crystal growth along the [110] direction. It is noted that compact passivation surface layers of oxides protect these NWs from further oxidation, even after nearly two years of exposure to ambient conditions; furthermore, these NWs display homogeneous ferromagnetism along their axial direction revealing the domination of shape anisotropy on magnetic behavior. Importantly, the average value of magnetic induction strengths of Fe NWs (2.07 {±} 0.10 T) and Co NWs (1.83 {±} 0.15 T) is measured to be very close to the respective theoretical value, and it shows that the surface oxide layers do not affect the magnetic moments in NWs. Our results provide a useful synthesis approach for the fabrication of single-crystalline, defect-free metal NWs and give insight into the micromagnetic properties in ferromagnetic NWs based on the transmission electron microscopy measurements.
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http://dx.doi.org/10.1063/1.5145337DOI Listing
March 2020

Growth of High-Quality Superconducting FeSeTe Films on Pb(MgNb)TiO and Electric-Field Modulation of Superconductivity.

Authors:
Chenguang Mei Zhu Lin Ruixin Zhang Chengchao Xu Haoliang Huang Yongqi Dong Miao Meng Ye Gao Xi Zhang Qinghua Zhang Lin Gu Huaixin Yang Huanfang Tian Jianqi Li Yalin Lu Guangming Zhang Yonggang Zhao

ACS Appl Mater Interfaces 2020 Mar 25;12(10):12238-12245. Epub 2020 Feb 25.

Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.

Heterostructures composed of superconductor and ferroelectrics (SC/FE) are very important for manipulating the superconducting property and applications. However, growth of high-quality superconducting iron chalcogenide films is challenging because of their volatility and FE substrate with rough surface and large lattice mismatch. Here, we report a two-step growth approach to get high-quality FeSeTe (FST) films on FE Pb(MgNb)TiO with large lattice mismatch, which show superconductivity at only around 10 nm. Through a systematic study of structural and electric transport properties of samples with different thicknesses, a mechanism to grow high-quality FST is discovered. Moreover, electric-field-induced remarkable change of (superconducting transition temperature) is demonstrated in a 20 nm FST film. This work paves the way to grow high-quality films which contain volatile element and have large lattice mismatch with the substrate. It is also helpful for manipulating the superconducting property in SC/FE heterostructures.
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http://dx.doi.org/10.1021/acsami.9b18749DOI Listing
March 2020

Enhance the treatment of low strength wastewater at low temperature with the coexistence system of AnAOB and heterotrophic bacteria: Performance and bacterial community.

Authors:
Yufeng Lv Juejun Pan Tangran Huo Jianqi Li Sitong Liu

Sci Total Environ 2020 Apr 18;714:136799. Epub 2020 Jan 18.

Department of Environmental Engineering, Peking University, Beijing 100871, China; Key Laboratory of Water and Sediment Sciences, Ministry of Education of China, Beijing 100871, China. Electronic address:

The application of anammox process in mainstream wastewater treatment process is still facing challenges especially at the low temperature. To resolve this problem, the coexistence system of anaerobic ammonia-oxidizing bacteria (AnAOB) and heterotrophic bacteria (HB) was built in this study. The nitrogen removal efficiency mainly maintained at above 90% during the process of temperature reducing from 35 °C to 10 °C. The nitrogen removal rate were 0.30 g N·L·d at both 25 and 15 °C and 0.10 g N·L·d at 10 °C, respectively. Analysis of 16S rRNA genus sequencing revealed that as the temperature reduced to 10 °C, the Denutrotisoma genera presented a downward trend but Comamonadaceae genera showed an upward trend. At 10 °C, the contrast of anammox activities between granular and flocculent sludge in the system revealed that although the abundance of anammox genera was much lower in flocculent sludge than that in granular sludge, the anammox activities showed no significant discrepancy. And the abundance of Comamonadaceae and Chloroflexales genera were much higher in flocculent sludge than those in granular sludge, presenting their key roles to anammox activity at low temperature. The Circos diagram and Cluster of orthologous Group of protein functional predication showed that the functional abundance related to interaction among microbial communities were higher in flocculent sludge but those related to self-growth was higher in granular sludge. This result indicated the significance of the interactions based on the microbial diversity in the application of annamox process at low temperature.
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http://dx.doi.org/10.1016/j.scitotenv.2020.136799DOI Listing
April 2020

Topics on quantitative liver magnetic resonance imaging.

Authors:
Yì Xiáng J Wáng Xiaoqi Wang Peng Wu Yajie Wang Weibo Chen Huijun Chen Jianqi Li

Quant Imaging Med Surg 2019 Nov;9(11):1840-1890

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Electronic Science, East China Normal University, Shanghai 200062, China.

Liver magnetic resonance imaging (MRI) is subject to continuous technical innovations through advances in hardware, sequence and novel contrast agent development. In order to utilize the abilities of liver MR to its full extent and perform high-quality efficient exams, it is mandatory to use the best imaging protocol, to minimize artifacts and to select the most adequate type of contrast agent. In this article, we review the routine clinical MR techniques applied currently and some latest developments of liver imaging techniques to help radiologists and technologists to better understand how to choose and optimize liver MRI protocols that can be used in clinical practice. This article covers topics on (I) fat signal suppression; (II) diffusion weighted imaging (DWI) and intravoxel incoherent motion (IVIM) analysis; (III) dynamic contrast-enhanced (DCE) MR imaging; (IV) liver fat quantification; (V) liver iron quantification; and (VI) scan speed acceleration.
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http://dx.doi.org/10.21037/qims.2019.09.18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6902134PMC
November 2019

Development of analytical ultrafast transmission electron microscopy based on laser-driven Schottky field emission.

Authors:
Chunhui Zhu Dingguo Zheng Hong Wang Ming Zhang Zhongwen Li Shuaishuai Sun Peng Xu Huanfang Tian Zian Li Huaixin Yang Jianqi Li

Ultramicroscopy 2020 Feb 10;209:112887. Epub 2019 Nov 10.

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China; Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China. Electronic address:

A new design scheme for ultrafast transmission electron microscopy (UTEM) has been developed based on a Schottky-type field emission gun (FEG) at the Institute of Physics, Chinese Academy of Sciences (IOP CAS). In this UTEM setup, electron pulse emission is achieved by integrating a laser port between the electron gun and the column and the resulting microscope can operate in either continuous or pulsed mode. In pulsed mode, the optimized electron beam properties are an energy width of ~0.65 eV, micrometer-scale coherence lengths and sub-picosecond pulse durations. The potential applications of this UTEM, which include electron diffraction, high-resolution imaging, electron energy loss spectroscopy, and photon-induced near-field electron microscopy, are demonstrated using ultrafast electron pulses. Furthermore, we use a nanosecond laser (~10 ns) to show that the laser-driven FEG can support high-quality TEM imaging and electron holography when using a stroboscopic configuration. Our results also indicate that FEG-based ultrafast electron sources may enable high-performance analytical UTEM.
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http://dx.doi.org/10.1016/j.ultramic.2019.112887DOI Listing
February 2020

Structural changes of cerebellum and brainstem in migraine without aura.

Authors:
Zhaoxia Qin Xin-Wei He Jilei Zhang Shuai Xu Ge-Fei Li Jingjing Su Yan-Hui Shi Shiyu Ban Yue Hu Yi-Sheng Liu Mei-Ting Zhuang Rong Zhao Xiao-Lei Shen Jianqi Li Jian-Ren Liu Xiaoxia Du

J Headache Pain 2019 Sep 2;20(1):93. Epub 2019 Sep 2.

Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, School of Physics and Electronic Science, East China Normal University, 3663 North Zhong-Shan Road, 200062, Shanghai, People's Republic of China.

Background: Increasing evidence has suggested that the cerebellum is associated with pain and migraine. In addition, the descending pain system of the brainstem is the major site of trigeminal pain processing and modulation and has been discussed as a main player in the pathophysiology of migraine. Cerebellar and brainstem structural changes associated with migraineurs remain to be further investigated.

Methods: Voxel-based morphometry (VBM) (50 controls, 50 migraineurs without aura (MWoAs)) and diffusion tensor imaging (DTI) (46 controls, 46 MWoAs) were used to assess cerebellum and brainstem anatomical alterations associated with MWoAs. We utilized a spatially unbiased infratentorial template toolbox (SUIT) to perform cerebellum and brainstem optimized VBM and DTI analysis. We extracted the average diffusion values from a probabilistic cerebellar white matter atlas to investigate whether MWoAs exhibited microstructure alterations in the cerebellar peduncle tracts.

Results: MWoAs showed decreased fractional anisotropy (FA) in the vermis VI extending to the bilateral lobules V and VI of the cerebellum. We also found higher axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) in the right inferior cerebellum peduncle tract in MWoAs. MWoAs exhibited both reduced gray matter volume and increased AD, MD and RD in the spinal trigeminal nucleus (SpV).

Conclusion: MWoAs exhibited microstructural changes in the cerebellum and the local brainstem. These structural differences might contribute to dysfunction of the transmission and modulation of noxious information, trigeminal nociception, and conduction and integration of multimodal information in MWoAs. These findings further suggest involvement of the cerebellum and the brainstem in the pathology of migraine without aura.
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http://dx.doi.org/10.1186/s10194-019-1045-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6734280PMC
September 2019

Altered Spontaneous Activity and Functional Connectivity in the Posterior Pons of Patients With Migraine Without Aura.

Authors:
Zhaoxia Qin Xin-Wei He Jilei Zhang Shuai Xu Ge-Fei Li Jingjing Su Yan-Hui Shi Shiyu Ban Yue Hu Yi-Sheng Liu Mei-Ting Zhuang Rong Zhao Xiao-Lei Shen Jianqi Li Jian-Ren Liu Xiaoxia Du

J Pain 2020 Mar - Apr;21(3-4):347-354. Epub 2019 Aug 7.

Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, School of Physics and Materials Science, East China Normal University, Shanghai, China. Electronic address:

The brainstem has been discussed as the main player in the pathogenesis of migraine. Dysfunctional brainstem nuclei and their abnormal connections to other key brain centers may contribute to headache and other symptoms of migraine. In the present study, 32 patients with migraine without aura (MWoA) and 32 age- and sex-matched healthy controls (HCs) underwent resting-state fMRI scans. We used masked independent analysis (mICA) to investigate whether patients with MWoA exhibited abnormal brainstem nuclei-cortical functional connectivity (FC). The mICA can suppress adjacent physiological noise and prevent results from being driven by the much stronger signals of the surrounding structures. Regional homogeneity (ReHo) was used to investigate whether the brainstem regions with abnormal FC to other brain areas exhibited abnormal regional neuronal activity. Patients with MWoA showed significantly weaker FC between the posterior pons and the left superior parietal lobule, the left middle temporal gyrus, and the left middle frontal gyrus. Furthermore, patients with MWoA exhibited significantly decreased ReHo values in the posterior pons compared with HCs, and the posterior pons ReHo value was significantly negatively correlated with HIT-6 scores in the MWoA group. Patients with MWoA exhibited functional abnormalities in the posterior pons and weakened connections between the posterior pons and several key cortical brain areas involved in pain processing during the resting state. PERSPECTIVE: This study provided increased evidence that the pons is involved in the pathophysiological mechanism of migraine, and weakened connections suggest that the touch and pain sensation of migraine sufferers may not be properly relayed to cortical processing areas, which may be associated with the pathogenesis of MWoA.
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http://dx.doi.org/10.1016/j.jpain.2019.08.001DOI Listing
August 2019

Mnemonic vulnerability induced by post-activation time-dependent new-learning.

Authors:
Fengtao Shen Xingxia Chen Jianqi Li Weicong Cao Yixuan Ku Jue Wu Yue Cui Zhaoxin Wang Huimin Wang Sze Chai Kwok

Neurobiol Learn Mem 2019 10 17;164:107047. Epub 2019 Jul 17.

Shanghai Key Laboratory of Brain Functional Genomics, Key Laboratory of Brain Functional Genomics Ministry of Education, School of Psychology and Cognitive Science, East China Normal University, Shanghai 200062, China; Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China; NYU-ECNU Institute of Brain and Cognitive Science at NYU Shanghai, Shanghai 200062, China. Electronic address:

Reactivation renders consolidated memory labile again, and the ensuing temporary reconsolidation process is highly susceptible to mnemonic modification. Here, we show that memories in such an unstable state could be influenced by sheer behavioral means, bypassing the need for pharmacological intervention. Across several experiments using a "face-location association" paradigm in which participants experienced a "Learning - New-learning - Final-test" procedure, we demonstrate that reactivated memory traces were hampered when the new learning was strategically administered at between 0-min and 20-min delay. Using fMRI, we further advance our theoretical understanding that this lability can be mechanistically explained by the differential activation in the hippocampal-amygdala memory system implicated by the post-activation new-learning whereas the mnemonic intrusion caused by newly learned memories is efficaciously reconciled by the left inferior frontal gyrus.
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http://dx.doi.org/10.1016/j.nlm.2019.107047DOI Listing
October 2019

Self-adapting multi-peak water-fat reconstruction for the removal of lipid artifacts in chemical exchange saturation transfer (CEST) imaging.

Authors:
Yu Zhao Xu Yan Zhongshuai Zhang Weiwei Zhao Zhenzhi Liu Jianqi Li

Magn Reson Med 2019 11 26;82(5):1700-1712. Epub 2019 Jun 26.

Shanghai Key Laboratory of Magnetic Resonance, School of Physics and Materials Science, East China Normal University, Shanghai, China.

Purpose: Artifacts caused by strong lipid signals pose challenges in body chemical exchange saturation transfer (CEST) imaging. This study aimed to develop an accurate water-fat reconstruction method based on the multi-echo Dixon technique to remove lipid artifacts in CEST imaging.

Theory And Methods: It is well known that fat has multiple spectral peaks. Furthermore, RF pulses in CEST preparation saturate each fat peak at different levels, complicating fat modeling. Therefore, a self-adapting multi-peak model (SMPM) is proposed to update relative amplitudes of fat peaks using numerical calculation. With the SMPM-based updating, nonlinear least-squares fitting combined with IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation) algorithms was used for water-fat reconstruction and B mapping. The proposed method was compared with the reported 3-point Dixon method and the fixed multi-peak model in a phantom study using a fat-free Z-spectrum obtained from MR spectroscopy acquisition as the ground truth. This method was also validated by in vivo experiments on human breast.

Results: In the phantom experiments, the Z-spectrum from the SMPM-based method agreed well with the fat-free Z-spectrum from CEST-PRESS (point-resolved spectroscopy), validating the effective removal of lipid artifacts, while a decrease or a rise that appeared at -3.5 ppm was observed in the Z-spectrum from the 3-point method and the FMPM-based method, respectively. In the in vivo experiments, no lipid artifacts were observed in the Z-spectrum or the amide CEST map from the SMPM-based method in the fibro-glandular region of the breast with high fat fractions.

Conclusion: The SMPM-based method successfully removes lipid artifacts and significantly improves the accuracy of CEST contrast.
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http://dx.doi.org/10.1002/mrm.27859DOI Listing
November 2019

Cerebellar functional abnormalities in early stage drug-naïve and medicated Parkinson's disease.

Authors:
Shuai Xu Xin-Wei He Rong Zhao Wei Chen Zhaoxia Qin Jilei Zhang Shiyu Ban Ge-Fei Li Yan-Hui Shi Yue Hu Mei-Ting Zhuang Yi-Sheng Liu Xiao-Lei Shen Jianqi Li Jian-Ren Liu Xiaoxia Du

J Neurol 2019 Jul 28;266(7):1578-1587. Epub 2019 Mar 28.

Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, School of Physics and Materials Science, East China Normal University, 3663 North Zhong-Shan Road, Shanghai, 200062, People's Republic of China.

Parkinson's disease (PD) is a progressive neurological degenerative disorder characterized by impaired motor function and non-motor dysfunctions. While recent studies have highlighted the role of the cerebellum in PD, our understanding of its role in PD remains limited. In the present study, we used resting-state fMRI to evaluate dysfunctions within the cerebellum in PD patients treated with medication and drug-naïve PD patients. We applied amplitude of low-frequency fluctuation (ALFF) and degree centrality (DC) analysis methods. Thirty-one patients with early stage PD (22 drug-naïve and 9 medicated patients) and 31 gender- and age-matched healthy controls were recruited in this study. ALFFs increased in the left cerebellar areas (lobules VI/VIIb/CruI/CruII and the dentate gyrus) and right cerebellar areas (lobules VI/VIIb/VIIIa/CruI/CruII and the dentate gyrus) of all PD patients and in the left and right cerebellar areas (lobules VI/VIIb/CruI and the dentate gyrus) of drug-naive PD patients but were not significantly changed in medicated PD patients. DC increased in the right cerebellar areas of all PD patients and medicated PD patients. All PD patients and all drug-naive PD patients showed significantly weaker functional connectivity (FC) between the left cerebellum and the left medial frontal gyrus. However, FC was significantly stronger between the right cerebellum and the left precentral and right middle occipital gyri in the medicated PD patients than in controls. Furthermore, a correlation analyses revealed that ALFF z scores in the left cerebellum (lobule VI) and right cerebellum (lobule VI/CruI and dentate gyrus) were negatively correlated with Mini-Mental State Examination (MMSE) scores in all PD patients and drug-naive patients. These results indicate that the cerebellum plays an important role in PD, mainly by exerting a compensatory effect in early stage PD. Additionally, antiparkinsonian medication would modified PD-induced changes in local neural activity and FC in PD patients. The results of this study offer novel insights into the roles of the cerebellum in early stage drug-naïve PD.
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http://dx.doi.org/10.1007/s00415-019-09294-0DOI Listing
July 2019

3D texture analyses within the substantia nigra of Parkinson's disease patients on quantitative susceptibility maps and R2 maps.

Authors:
Gaiying Li Guoqiang Zhai Xinxin Zhao Hedi An Pascal Spincemaille Kelly M Gillen Yixuan Ku Yi Wang Dongya Huang Jianqi Li

Neuroimage 2019 03 19;188:465-472. Epub 2018 Dec 19.

Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062, China. Electronic address:

Iron accumulation in the substantia nigra (SN) is spatially heterogeneous, yet no study has quantitatively evaluated how the texture of quantitative susceptibility maps (QSM) and R2 might evolve with Parkinson's disease (PD) and healthy controls (HC). The aim of this study was to discriminate between patients with PD and HC using texture analysis in the SN from QSM and R2 maps. QSM and R2 maps were obtained from 28 PD patients and 28 HC on a clinical 3T MR imaging scanner using 3D multi-echo gradient-echo sequence. The first- and second- order texture features of the QSM and R2 images were obtained to evaluate group differences using two-tailed t-test. After correction for multiple comparisons, for the first-order analysis, the susceptibility of SN from patients with PD was significantly greater (p = 0.017) compared with the SN from HC. For the second-order texture analysis, angular second moment, entropy, and sum of entropy showed significant differences in QSM (p < 0.001) and R2 maps (p < 0.01). In addition, correlation, contrast, sum of variance and difference of variance, significantly separated the subject groups in QSM maps (p < 0.05) but not in R2 images. Receiver operating characteristic analysis showed that entropy and sum of entropy of the QSM maps in the SN yielded the highest performance for differentiating PD patients from HC (area under the curve = 0.89). In conclusion, most first- and second- order QSM texture features successfully distinguished PD patients from HC and significantly outperformed R2 texture analysis. The second-order texture features were more accurate and sensitive than first-order texture features for classifying PD patients.
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http://dx.doi.org/10.1016/j.neuroimage.2018.12.041DOI Listing
March 2019

Design, synthesis and biological evaluation of novel, orally bioavailable pyrimidine-fused heterocycles as influenza PB2 inhibitors.

Authors:
Jian Xiong Jingjing Wang Guoping Hu Weili Zhao Jianqi Li

Eur J Med Chem 2019 Jan 10;162:249-265. Epub 2018 Nov 10.

Novel Technology Center of Pharmaceutical Chemistry, Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, PR China. Electronic address:

With the aim to identify novel influenza PB2 inhibitors with high potency and excellent pharmacokinetic parameters, we have designed and synthesized two new series of pyrimidine-fused heterocycle derivatives based on two generations of co-crystal structures. Docking studies with the newly disclosed PDB structure guided the second round of rational design and led to the discovery of 25m, 25o and 25p as representative compounds with improved potency (EC < 1 nM). After pinpointing the metabolic labile site, the CN replacement of compound 25p successfully produced compound 29c, which demonstrated highly improved PK properties (Cl = 1.3 mL/min/kg, PO AUC = 152 μM h at 10 mpk in mouse, F = 57%) and improved potency, emerging as a promising lead compound for the treatment of influenza A infection.
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http://dx.doi.org/10.1016/j.ejmech.2018.11.015DOI Listing
January 2019

A multifunctional SERS sticky note for real-time quorum sensing tracing and inactivation of bacterial biofilms.

Authors:
Jingxing Guo Ying Liu Yunlong Chen Jianqi Li Huangxian Ju

Chem Sci 2018 Jul 31;9(27):5906-5911. Epub 2018 May 31.

State Key Laboratory of Analytical Chemistry for Life Science , School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , P. R. China . Email:

Quorum sensing (QS) is crucial for bacterial survival and activity. Although detecting related signaling metabolites can reveal QS, a versatile platform for convenient real-time imaging of their secretion in the context of bacterial biofilms along with inhibition to the growth of biofilms is still highly desired. Here we develop a flexible sticky note with a sandwich structure by encapsulating gold nanostars between two pieces of hexagonal boron nitride layers, which can be easily pasted on natural biofilms to monitor in real-time the secreted signaling molecule by SERS imaging with high sensitivity and spatiotemporal resolution. Using and its pyocyanin secretion as a model and an internal standard for self-calibration of SERS signals, the sticky note achieves reliable quantification and a rapid response to the secretion as early as 1 h biofilm growth. With antibiotic loading, the multifunctional SERS sticky note also demonstrated effective inactivation of the bacterial biofilm with simultaneous evaluation of the inactivation effect. This multifunctional SERS sticky note provides a versatile platform for investigating bacterial behaviors and developing antibacterial therapeutics.
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http://dx.doi.org/10.1039/c8sc02078gDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050527PMC
July 2018

Hidden CDW states and insulator-to-metal transition after a pulsed femtosecond laser excitation in layered chalcogenide 1T-TaS Se .

Authors:
Kai Sun Shuaishuai Sun Chunhui Zhu Huanfang Tian Huaixin Yang Jianqi Li

Sci Adv 2018 07 20;4(7):eaas9660. Epub 2018 Jul 20.

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

The hidden (H) quantum state in 1T-TaS has sparked considerable interest in the field of correlated electron systems. Here, we investigate ultrafast switches to stable H charge density wave (H-CDW) states observed in 1T-TaS Se , with = 0 and 0.5 crystals, upon excitation with a single femtosecond laser pulse. In situ cooling transmission electron microscopy observations, initiated by a single femtosecond laser pumping with a low fluence, reveal a clear transition from a commensurate CDW phase () to a new CDW order with = (1 - δ) for the H-CDW state (δ = 1/9) accompanied by an evident phase separation. H-CDW domain relaxation then occurs and yields a stable metallic phase under a high-fluence excitation. Furthermore, electrical resistivity measurements show that the notable drop in = 0 and 0.5 samples associated with the appearance of H-CDW states depend on laser fluence and temperature. These results potentially provide a new perspective on the photodoping mechanism for the emergence of H-CDW states in the 1T-TaS Se family.
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http://dx.doi.org/10.1126/sciadv.aas9660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6054513PMC
July 2018

A metabolomic view of how low nitrogen strength favors anammox biomass yield and nitrogen removal capability.

Authors:
Yongzhao Guo Yunpeng Zhao Tingting Zhu Jianqi Li Ying Feng Huazhang Zhao Sitong Liu

Water Res 2018 10 26;143:387-398. Epub 2018 Jun 26.

Department of Environmental Engineering, Peking University, Beijing 100871, China; School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China. Electronic address:

The low yield of anaerobic ammonium oxidation (anammox) biomass has attracted great attention because of its difficulty to be abundantly enriched. Patterns of substrate supply greatly influence microbial metabolism and behavior. The present study proposed that low nitrogen strength was beneficial to anammox biomass yield and nitrogen removal when comparing a membrane bioreactor (MBR) operated at low nitrogen strength with short hydraulic retention time (HRT) (R-low; influent: fixed at 100 mg-N L) and one operated at high nitrogen strength with long HRT (R-stepwise; influent: 100-700 mg-N L). Different nitrite concentrations in the two MBRs would indicate discrepant environments, and inevitably resulted in the discrepant microbial responses for anammox community. In particular, we found that at low nitrogen strength, increased activities of purine and pyrimidine metabolism pathways provided more abundant nucleic acids for bacterial proliferation. More active reaction of lipid and protein synthesis favored the synthesis of cellular structure. Importantly, the metabolism of cheaper amino acids was more active under low nitrogen strength, which was coupled with higher metabolic flux and potentially more active exchange of costly amino acids as public goods. In this way, more energy could be saved and applied to biomass yield. Higher active bacterial diversity and more positive interactions among bacterial species in R-low further favored biomass yield and nitrogen removal. The present study highlighted the significant effect of substrate supply patterns on anammox, which is meaningful to overcome the current bottleneck of deficient anammox biomass for application in wastewater treatment.
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http://dx.doi.org/10.1016/j.watres.2018.06.052DOI Listing
October 2018

One-Pot Synthesis of Indole-3-acetic Acid Derivatives through the Cascade Tsuji-Trost Reaction and Heck Coupling.

Authors:
Dongsheng Chen Yuanyuan Chen Zhilong Ma Lei Zou Jianqi Li Yu Liu

J Org Chem 2018 06 29;83(12):6805-6814. Epub 2018 May 29.

Novel Technology Center of Pharmaceutical Chemistry , Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry , 285 Gebaini Road , Shanghai 201203 , People's Republic of China.

A practical palladium-mediated cascade Tsuji-Trost reaction/Heck coupling of N-Ts o-bromoanilines with 4-acetoxy-2-butenonic acid derivatives using a Pd(OAc)/P( o-tol)/DIPEA system is described for a straightforward synthesis of indole-3-acetic acid derivatives. This methodology was successfully applied to synthesize various substituted indole/azaindole-3-acetic acid derivatives and Almotriptan, which is a drug for the acute treatment of migraines. Moreover, a plausible cyclization mechanism has been proposed.
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http://dx.doi.org/10.1021/acs.joc.8b01056DOI Listing
June 2018

Quantification of Magnetic Surface and Edge States in an FeGe Nanostripe by Off-Axis Electron Holography.

Authors:
Dongsheng Song Zi-An Li Jan Caron András Kovács Huanfang Tian Chiming Jin Haifeng Du Mingliang Tian Jianqi Li Jing Zhu Rafal E Dunin-Borkowski

Phys Rev Lett 2018 Apr;120(16):167204

Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.

Whereas theoretical investigations have revealed the significant influence of magnetic surface and edge states on Skyrmonic spin texture in chiral magnets, experimental studies of such chiral states remain elusive. Here, we study chiral edge states in an FeGe nanostripe experimentally using off-axis electron holography. Our results reveal the magnetic-field-driven formation of chiral edge states and their penetration lengths at 95 and 240 K. We determine values of saturation magnetization M_{S} by analyzing the projected in-plane magnetization distributions of helices and Skyrmions. Values of M_{S} inferred for Skyrmions are lower by a few percent than those for helices. We attribute this difference to the presence of chiral surface states, which are predicted theoretically in a three-dimensional Skyrmion model. Our experiments provide direct quantitative measurements of magnetic chiral boundary states and highlight the applicability of state-of-the-art electron holography for the study of complex spin textures in nanostructures.
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http://dx.doi.org/10.1103/PhysRevLett.120.167204DOI Listing
April 2018

Cooperative inter- and intra-layer lattice dynamics of photoexcited multi-walled carbon nanotubes studied by ultrafast electron diffraction.

Authors:
Shuaishuai Sun Zhongwen Li Zi-An Li Ruijuan Xiao Ming Zhang Huanfang Tian Huaixin Yang Jianqi Li

Nanoscale 2018 Apr;10(16):7465-7471

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

Optical tuning and probing ultrafast structural response of nanomaterials driven by electronic excitation constitute a challenging but promising approach for understanding microscopic mechanisms and applications in microelectromechanical systems and optoelectrical devices. Here we use pulsed electron diffraction in a transmission electron microscope to investigate laser-induced tubular lattice dynamics of multi-walled carbon nanotubes (MWCNTs) with varying laser fluence and initial specimen temperature. Our photoexcitation experiments demonstrate cooperative and inverse collective atomic motions in intralayer and interlayer directions, whose strengths and rates depend on pump fluence. The electron-driven and thermally driven structural responses with opposite amplitudes cause a crossover between intralayer and interlayer directions. Our ab initio calculations support these findings and reveal that electrons excited from π to π* orbitals in a carbon tube weaken the intralayer bonds while strengthening the interlayer bonds along the radial direction. Moreover, by probing the structural dynamics of MWCNTs at initial temperatures of 300 and 100 K, we uncover the concomitance of thermal and nonthermal dynamical processes and their mutual influence in MWCNTs. Our results illustrate the nature of electron-driven nonthermal process and electron-phonon thermalization in the MWCNTs, and bear implications for the intricate energy conversion and transfer in materials at the nanoscale.
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http://dx.doi.org/10.1039/c8nr00432cDOI Listing
April 2018

Seed point discontinuity-based segmentation method for the substantia nigra and the red nucleus in quantitative susceptibility maps.

Authors:
Tian Guo Yang Song Jianqi Li Mingxia Fan Xu Yan Andi He Dongya Huang Chaomin Shen Guixu Zhang Guang Yang

J Magn Reson Imaging 2018 10 31;48(4):1112-1119. Epub 2018 Mar 31.

Shanghai Key Laboratory of Magnetic Resonance and Department of Physics and Material Science, East China Normal University, Shanghai, China.

Background: The automatic segmentation of cerebral nuclei in the quantitative susceptibility mapping (QSM) images can provide assistance for surgical treatment and pathological mechanism studies. However, as the most frequently used segmentation method, the atlas method provides unsatisfactory results when segmenting the substantia nigra (SN) and the red nucleus (RN).

Purpose: To propose and evaluate an improved automatic method based on seed points-discontinuity for segmentations of the SN and the RN in QSM images.

Study Type: Prospective.

Subjects: In all, 22 subjects, 11 patients with Parkinson's disease (PD), and 11 healthy subjects (mean age of 68.0 ± 6.9 years) underwent MR scans.

Field Strength/sequence: 3T system and a 3D multiecho gradient echo sequence with monopolar readout gradient.

Assessment: Manual segmentations by two radiologists (both with over 10 years of experience in neuroimaging) were used to establish a baseline for assessment. The Dice coefficient and the center-of-gravity distance was employed to evaluate the segmentation accuracy.

Statistical Tests: The mean value and standard deviation of the Dice coefficient and center-of-gravity distance were calculated separately to compare segmentation results from the proposed method, the level set method, the atlas method (including the single-atlas method and the multi-atlas majority voting method).

Results: The statistical results of Dice coefficient of the SN and the RN between the ground truth and the segmentation were 0.79 ± 0.14 and 0.77 ± 0.06 for the proposed method, 0.40 ± 0.10 and 0.65 ± 0.09 for the level set method, 0.68 ± 0.09 and 0.64 ± 0.07 for the single-atlas method, 0.70 ± 0.06 and 0.68 ± 0.05 for the multi-atlas majority voting method, respectively. The proposed method also provides the lowest center-of-gravity distance value (1.05 ± 0.71 for the SN and 0.74 ± 0.35 for the RN).

Data Conclusion: The segmentation results of the proposed method performed well on the in vivo data and were closer to the manual segmentation than the atlas method.

Level Of Evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;48:1112-1119.
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http://dx.doi.org/10.1002/jmri.26023DOI Listing
October 2018